Twisted Love by Ana Huang
This romance novel was originally published in 2021, but it found new life on TikTok recently. It has over a million total ratings, with an average rating of 3.7.
Silvana Reyes Lopez recommends this as a stand-out best friend romance (specifically, a sibling-of-your-best-friend romance): “Ava’s brother, Josh, is going to Central America for a job opportunity, so he’s leaving his perfectly nice apartment that happens to be next door to Ava’s. Also, Josh is worried about leaving Ava alone. After her traumatic childhood, Josh just wants the best for his sister. That’s why he tells his best friend Alex Volkov to keep an eye on her. Alex, the mysterious young billionaire, isn’t so thrilled about this new turn in his life, but slowly, he starts to spend time with Ava and falls for her.
Although there are far more secrets left to uncover in both of their lives, Ava and Alex will try their hardest to get to their happily ever after.”